Ravensdown is no longer using trains for its Napier plant, meaning more trucks will use Marine Parade in spring and autumn ferrying fertiliser from Napier Port.
Communications manager Gareth Richards said for the last three years 85 per cent of product shipped from the Awatoto plant was freighted by road or coastal ship and the cessation of rail was an amicable agreement.
The farmer-owned co-operative is the only user of the fertiliser carriages and KiwiRail proposed increased charges to cover upkeep.
"The issue for KiwiRail and Ravensdown is the very high expenditure associated with the maintenance of ageing rolling stock," he said.
"This led to KiwiRail proposing a rail freight rate that was just uneconomic. If more businesses had used the rail freight option over the years, then of course those maintenance costs would have been spread more evenly."
The company would work with the community "so that the impact of road traffic is managed appropriately".
Ravensdown has used its rail siding since the 1950s and last year there were 180 rail trips on scheduled trains during spring and autumn.
The final rail trip was last month and the company's shunting locomotive has been sold to a Napier man.
A KiwiRail spokesperson said until recently it carried Ravensdown product to New Plymouth, Wanganui, Utiku and Feilding from Awatoto.
"It was seasonal traffic and we were moving up to seven wagons a day, primarily during spring and autumn, on existing freight services," she said.
"We had also moved product to Gisborne prior to the mothballing of the line between Napier and Gisborne."
There is little chance of the Napier to Palmerston North line being closed due to Napier Port sourcing freight throughout the lower North Island.
"There is still considerable other freight traffic moving between Palmerston North and Napier, so the line will continue to be used and no services cancelled. In particular forestry volumes moving by rail in the lower North Island are growing and we expect this will fill any gap."